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Old Variants. Old variants were those in distribution until near the end of August, 2019. Our decrypter supports offline ID's for almost all older variants, and can decrypt files for those with offline ID's without needing any help. For online ID's, it's necessary to supply file pairs to our online submission form so that the decrypter can be "trained" how to decrypt your files. A list of extensions from older variants can be found at the bottom of this post.

What is a file pair? This refers to a pair of files that are identical (as in they are the exact same file), except one copy is encrypted and the other is not. Our decryption service can analyze the differences between an encrypted file and an original unencrypted copy of the same file, allowing it to determine how to decrypt that type of file. For most victims with an older variant of STOP/Djvu, submitting file pairs will be the only way they will get their files back.

File pairs only work for one type of file. Due to the way encryption works in STOP/Djvu, file pairs can only help the decryption service figure out how to decrypt one type of file. For instance, if you submit a file pair for an MP3 file, then the decrypter will be able to decrypt all of your other MP3 files, however it won't be able to decrypt any other type of file. There are some exceptions to this, such as certain newer Microsoft Office documents (such as DOCX and XLSX) since those files are technically ZIP archives.

The decrypter can't decrypt all of my pictures even though I submitted file pairs for them? JPEG/JPG images have a format oddity that causes file pairs to be specific to each source of pictures, rather than the file format in general. As an example, if you have pictures from two different cameras, and submit a file pair from the group of pictures from one of the cameras, then the decrypter will only be able to decrypt files from the camera that the file pair came from. In order to decrypt all JPEG/JPG images, you will need to submit file pairs from every source you've obtained those pictures from.